This invention relates to containers for enclosing a transformer mounted on a pad. More particularity the present invention relates to transformer containers having a transformer tank and a transformer door pivotally connected to the tank and detachably locked to a transformer. In greater particularity, the present invention relates to padmounted transformer containers having a transformer tank cover detachably connected to the transformer tank for covering an access portal defined thereby.
Distribution transformers are used to reduce the voltage from the power lines, that are used to distribute power, to a voltage that is safe to use by the end user (typically a home or business). With the progressive use of underground power lines, the use of pad mounted transformers has become more common. The pad mounted transformer is typically attached to and is supported by a concrete pad or a pad made of other materials with similar durability. The transformer enclosure has two basic components, the wiring compartment that contains the connections for the power distribution system and the tank that contains the transformer""s core and coil assembly immersed in oil. Electrical connections extend from the core and coil through a front panel of the transformer tank into the wiring compartment enabling connection to the power distribution system.
The wiring compartment is accessed by a door, which is connected at a pivot point on the oil compartment tank and, in combination with the transformer tank, forms the complete enclosure wherein the transformer is housed. The door is secured by a bolt and by a padlock, limiting access to authorized personnel only. The tank oil compartment is a sealed container, which houses the core and coil assembly and the oil. Typically the oil compartment is of welded construction, including a cover that is welded into place forming a completely welded container. Although the welded tank and cover provides a good oil compartment, it is difficult to gain entry to the tank to perform repairs, change fuses and allow inspections.
One of the primary functions of the transformer enclosure is to prevent access to the transformer by unauthorized individuals. Accordingly, the transformer cover door is typically locked to the transformer pad. The door may utilize a lock as simple as a pad lock. More common is the use of a transformer sill bolted to the transformer pad and supporting the transformer door which is pivotally connected to the transformer tank. The transformer sill houses a locking mechanism which may be used to selectively engage and lock the transformer door to the transformer sill.
As stated above, it would be convenient if the interior of the transformer tank could be periodically accessed to perform maintenance inspection. Since transformer tanks are commonly designed with a welded cover, easy access to the interior of the transformer tank is not possible. To prevent authorized access, the transformer tank will include a removable transformer tank cover which blocks unauthorized access to the interior of the transformer tank.
In U.S. Pat. No. 4,533,786 issued to Borgmeyer et al., the tank cover is a flat sheet of steel(124) welded to the tank. Obviously, access to the tank would require a cutting torch. A similar arrangement is shown in U.S. Pat. No. 4,559,699 issued to Owen, et al.
There are transformer tank covers that are secured using a series of bolts connected to the tank and extending through a plurality of holes defined in the transformer tank cover. See U.S. Pat. No. 3,376,086 issued to J. L. Fisher. The transformer tank cover is secured to the transformer tank with a plurality of threaded bolts and nuts. To prevent unauthorized users from removing the nuts, a false cover may be pivotally mounted to the transformer tank cover and those bolts associated therewith. The false cover is then locked to the transformer tank. It should be apparent; however, that the false cover adds additional manufacturing cost and additional removal time to access the interior of the tank.
What is needed is a transformer container having a transformer tank cover thereon which will prevent unauthorized access to the transformer tank interior and at the same time, facilitate ease of manufacture and minimize manufacturing costs and limit the time necessary for authorized access to the interior of the tank.
The present invention includes a transformer tank having a front panel, two side panels and a rear panel all connected to a bottom. The transformer tank is connected to and supported by a pad. The transformer tank also includes a top panel having a rim that defines a portal through which the interior of the tank may be accessed. One or more holes are defined by the top panel proximate a rearward edge thereof. Note that the rear panel is connected to the top panel between the holes and the portal such that the holes do not communicate with the interior of the tank. A transformer cover sill is bolted to the pad and to the transformer tank and has a locking mechanism seated therein. A transformer door is pivotally connected to the top panel of the transformer tank and may be pivoted to a closed position in contact with the transformer sill and selectively locked thereto by the locking mechanism. The transformer door, the transformer sill, the pad and the transformer tank form a lockable enclosure with which the holes defined by the top panel communicate.
The present invention also includes a transformer tank cover having a flange thereon for engaging a portion of the rim opposite the holes. The flange is substantially xe2x80x9cUxe2x80x9d shaped in cross-section; having a first member that extends from an underside of the cover, a second portion connected to the first portion and extending substantially parallel to the cover past a lateral edge thereof, and a third portion connected to the second portion and extending upward in substantially parallel relation to the first portion. The third portion defines an engaging edge that is spaced in substantially parallel relation to the lateral edge of the transformer tank cover. The engaging edge is spaced laterally of the transformer tank cover a distance greater than the thickness of the rim; however, if the transformer cover was supported on a horizontal plane, the engaging edge would be spaced below the lateral edge of the transformer cover a distance substantially equal to the width of the rim.
Note that this particular arrangement of the flange and the engaging edge relative to the lateral edge of the transformer tank cover facilitates the insertion of the engaging edge below the rim while the lateral edge of the transformer tank cover is positioned above the rim with the rim therebetween. The transformer tank cover may then be lowered to a closed position in contact with the top panel with the rim engaged between the lateral edge of the transformer tank cover and the engaging edge of the flange and in substantially pressed abutmant with both. The flange thus partially secures the transformer tank cover to the top panel of the transformer tank. The transformer tank cover also includes one or more threaded studs connected to an underside of the transformer tank cover. The threaded studs extend substantially perpendicular to the transformer tank cover for reception within and extension through the holes defined in the top panel of the transformer tank. A gasket is secured to the transformer tank cover and creates a seal between the transformer tank cover and the top panel. The gasket is positioned inward of the lateral edge of the transformer tank cover to prevent tampering.
In operation the transformer tank cover is tilted in angular relation to the top panel of the transformer tank, the flange is positioned beneath the rim and the transformer tank cover is rotated downward in substantially coplaner contact with the top panel of the transformer tank. The threaded studs are received through the holes as the transformer tank cover comes to rest on the top panel. The transformer cover hood is lifted to allow access to the threaded stud. A plurality of threaded nuts are used to threadably engage a threaded end of each post to secure the transformer tank cover to the top panel of the transformer tank. The transformer tank hood is then closed and locked to prevent access, not only to the power distribution system contained therein, but also the nuts and threaded studs securing the transformer tank cover.
The foregoing invention provides a transformer tank container that is simple and inexpensive to manufacture that utilizes a transformer tank cover that may be easily secured to the transformer tank and which, in combination with the specific arrangement of the front panel of the transformer tank, and its positioning between the holes and the portal defined on the top panel of the transformer tank, will prevent access by an unauthorized individual. No additional locking mechanism is required other than that commonly used to secure the transformer door to the transformer sill.